After much contemplation I realized that my previous approach to solving this execute query template function problem was more wrong than right. Several days of staring at and reading about variadic templates later I figured out the correct way to accomplish my goal.
I finally got back to working on this POC, and I was able to get it mostly working. The only issue right now is that the template magic is attempting to create code for which the types don't match and don't cast decay nicely. That is if you try to assign a std::string to a tuple. Hopefully I can fix this with a bit of massaging.
Adding sqlite proof-of-concept. This code does not compile due to some template issues but I want to keep track of it none the less.